1. Field of the Invention
The present invention relates to a fuel reforming device, and more particularly to a plasma reformer and an internal-combustion engine system having the same.
2. Description of the Related Art
With the advancement of the industry, the consumptions of the conventional energy sources, such as coal, oil, and natural gas, etc., are increased duratively. Since those natural energy sources have limited reserves, new energy sources must be developed to replace the conventional energy sources. A fuel cell is an important new power device with practical values.
Simply speaking, the fuel cell generates electrical power via a redox reaction. Compared with the other modes of generating electricity, the fuel cell has advantages, such as lustration and high efficiency. Basically, the fuel cell uses hydrogen as a fuel, and uses oxygen as an oxidation reagent. The output of the electrical power generated by the fuel cell is proportional to the consumption of the reactants.
A conventional method of obtaining the hydrogen uses a hydrocarbon fuel (for example, natural gas, liquefied petroleum gas (LGP), gasoline, diesel oil, and other fuel oils, etc.) to produce the hydrogen through several steps (including a step of initializing and reforming, and several following steps of purifying). The conventional methods of reforming the hydrocarbon are steam reforming (SR) method, auto thermal reforming (ATR) method, and partial oxidation (POX) method. The purifying step includes a step of desulfurizing, a step of high/low temperature water shift reaction, a step of selective oxidizing carbon monoxide or a step of selective methylating carbon monoxide. In addition, a method of using thin film reactor or filter having an excellent property of selecting the hydrogen is performed to produce the hydrogen. However, the technology of the method is not ripe, and the cost of the method is high so that the method is not popular.
The application of the fuel cell is embarrassed since the infrastructure for supplying hydrogen is not ripe. Furthermore, the hydrogen has a low volumetric energy density such that compared with the hydrocarbon fuel, the hydrogen is difficult to be stored and carried. To eradicate the above problems, a method uses a distributed reformer to transform the hydrocarbon into a gas containing abounding hydrogen to supply the fuel cell.
Conventional reformers must select a special catalyst corresponding to the fuel, to accelerate the reaction. Since the catalyst is easy to be covered by the diversified sulfides or the deposited carbon to be poisoned or lost its active property, the catalyst must be replaced timely so as to increase the cost.
Since the plasma can accelerate the reaction instead of the catalyst, direct current (DC) plasma reformers are paid attention in recently. The conventional DC plasma reformers form DC arc plasma under low voltage and high current. Thus electrodes are easy to be eroded or be melted so that the electrodes have a short using-time. Diversified methods are used to solve the above problem, such as using cooling water or special electrode material to increase the lifetime of the electrodes. Another method is increasing little pressure to increase the resistance in the gas discharge atmosphere such that the electrodes can be protected by decreasing currents and increasing voltages. However, the conventional DC arc plasma fuel reformer lost biggish energy, the electric power is generally larger than real need. The output of the power supply is over a kilowatt. Therefore, these methods cannot effectively solve the problem that the lifetime of the electrodes is short.